The present invention relates to touch fasteners in general, and more specifically, to touch fasteners for incorporation by molding into molded articles.
Hook and loop type separable touch fasteners, such as those sold by the assignee of this application under the trademark Velcro, are well-known and are used to join two members detachably to each other. This type of fastener has two components. Each has a flexible substrate material having one component of the fastening system on a fastening surface thereof. One component is typically comprised of resilient hooks while the other is comprised of loops, and when the two surfaces are pressed together they interlock to form a releasable engagement.
Separable fasteners are used in the manufacture of automobile seats in the attachment of an upholstered seat cover to a polyurethane foam bun. One portion of the separable fastener is incorporated onto the surface of the polyurethane foam bun during the foam molding process. The mating portion of the separable fastener is attached to the seat cover to provide releasable attachment to the foam bun. The separable fastener assembly used in the foam mold for incorporation in the bun surface typically comprises the hooked portion of a separable fastener. This hook portion is characterized by a base carrying resilient hooks on a fastening surface. The opposite, non-fastening surface of the base may carry anchor projections to become incorporated into the foam to provide stable attachment of the separable fastener assembly to the foam article. It is also common for a backing layer or substrate to mate with the non-fastening face of the base. The substrate may be of a material that is more conducive to handling, of the component or its adherence to other articles. Anchor projections may also project from the substrate. Further, other components can be sandwiched between the substrate and the base.
A protective layer, such as a thin plastic film, may be placed over the resilient hooks, to prevent incursion of foam into the hooks during the molding process, since significant foam contamination of the hooks would affect their ability to engage with the mating portion of the fastener attached to the seat cover. Alternatively, an elastomeric cover that intimately surrounds the hooks, except for a small portion at their tips, can also be used. After the molded article is fabricated and removed from the mold, the elastomeric material is removed.
In some assemblies, a magnetically attractive shim is attached to the base to facilitate placement of the assembly in a valley (also known as a trench or trough) of the mold cavity wall, which is equipped with magnets. The shim also helps secure the hook-carrying face of the component tightly against the mold wall, thereby further minimizing incursion of the foam into the hooks. The assemblies may be referred to as "mold-in" fasteners or assemblies, due to their use in such molded products.
The shim can be incorporated into different locations in the assembly. It can be sandwiched between the hook carrying base and a substrate or backing layer, either temporary or permanent. It can be located centrally relative to the width of the hook-carrying base, or along its marginal edges. In cases where a thin plastic film is used to cover the hooks, the shim can be sandwiched between the plastic sheet and the hooks.
As mentioned above, it is also known to substantially cover the hook region with an elastomeric material that protects the hooks against incursion of the foam. It is known to include a magnetic attractant in this elastomeric material.
Known methods of adhering the protective film cover to the hook-carrying component include to use a long bead of hot melt adhesive there between. It is also known to include a magnetic attractant in this hot melt material.
The known methods all have drawbacks. With regard to the metal shim itself, it presents an extra component and an extra manufacturing step, thereby contributing to the cost of the assembly and the time for manufacturing a given length of material. The metal shim also contributes to the weight of the material. In the construction process, care must be taken that workers are not cut by the metal strips. The metal limits the flexibility of the strip, and consideration must be taken of the thermal expansion and contraction properties of the various binders and additional layers that might be used to secure the strip to the substrate. The metal strip also curls and bows and generally makes handling the component unwieldy.
Considering those known assemblies that use either the protective plastic or the elastomeric cover to contain the metal shim, or a magnetic attractant, there are reasons to eliminate these protective covers, if possible. The protective covers also entail additional steps, in their manufacture, attachment to the fastener assembly, and removal from the fastener assembly after molding. All protective material must be removed from the hooks (or loops, if it be the loop carrying component molded into the article), or else the hooks (or loops) will not be exposed to fasten to the mating component. These extra steps must typically be conducted away from a normal high speed production line and contribute to the cost of the fastener assembly, the time for its manufacture, and also generate a relatively large volume of essentially waste material. Additionally, sometimes a residue from the cover material remains on the fastening component after removal, which is undesirable.
Thus, there is a great need for a touch fastener assembly that can be molded into a molded product, without the use of metal shims or protective covering for the fastener components. There is also a need to simplify the manufacture of such mold-in assemblies, to minimize their cost, production time, and the time to prepare the molded product for use. It is thus an object of the invention to facilitate a simple means for providing a magnetic attractability to the mold-in fastener assembly. It is another object of the invention to provide a light weight mold-in assembly that does not require a metal shim or protective covering for the fastener components, such as hooks.